1. Field of the Invention
The present invention relates to an image processing apparatus and an image processing method, and in particular to an image processing apparatus and image processing method that can restore image data that is more faithful to an original image, from image data on which another image processing apparatus has performed image processing.
2. Description of the Related Art
Digital multifunction peripherals (MFP) have conventionally been used in a standalone situation for copying use, but in recent years, as intranets and the Internet have become widely used, it has become possible to use MFPs via a network. An MFP connected to a network can, for example, receive image data that has been digitized by another MFP via the network, and print and file the received image data.
There are cases in which various types of image processing are performed in MFPs in order to improve the quality of image data obtained by reading a document with use of a scanner. For example, in order to improve the reproducibility of characters in a document, a method has been proposed in which a document is divided into character areas and photograph areas, and the character areas are edge-emphasized (e.g., see Japanese Patent Laid-Open No. H8-272952).
However, there are cases in which image processing differs depending on the type of MFP, and therefore if a MFP prints or files image data that has been digitized by a different type of MFP, it is possible for image degradation to occur. For example, in the image processing apparatus disclosed in Japanese Patent Laid-Open No. H8-272952, even in the case of a document image that has a low density and is low contrast (i.e., an image having a large amount of noise), characters on the background pattern can be reproduced favorably, and isolated points that appear in the character areas due to noise can be reduced. When the above apparatus outputs an image in a standalone situation, the use of such a function will improve the quality of the output image. However, when an output character image from an apparatus having such a function is compared to an output character image from an apparatus that does not have such a function, there are cases in which there are differences in portions other than the improved portion as well. For example, the lines in a binarized character image have been thinned down due to an edge-emphasizing process. This means that if these two types of MFPs input the same document by scanning, different images are output. This is not particularly a problem when MFPs are used in a standalone situation, such as copying.
However, when reading a document with an MFP, filing the read document as image data, and reusing the image data is taken into consideration, an image (particularly a character image) that has been read by different MFPs and should originally be the same will be output at different qualities. This leads to differences in the reproducibility and readability of characters in the filed image data, and can reduce the value of the filed document.